In Vivo Detection of Glutamate in Tomatoes by an Enzyme-Based Electrochemical Biosensor

Abstract

The in vivo and on-site detection of key physiology parameters in plants will be of great relevance for precision agriculture and food technology. In this work, a sensitive enzymatic glutamate sensor was successfully developed. To enhance the conductivity and catalytic ability and to fix the glutamate oxidase, Au–Pt nanoparticles were first deposited on screen-printed electrodes, and then carboxylated graphene oxide and carboxylated multiwalled carbon nanotubes were fabricated for the synthesis of the electrode. The detection range of the glutamate sensor is widest (2 μM to 16 mM) up to date, and its detection limit is relatively low (0.14 μM). A number of standard curves were built in the pH range of 3.5–7.5, which can be applied in various plants and fruits. Using this sensor, the glutamate level in tomatoes was determined in vivo. This glutamate sensor has important practical value in precision agriculture. Our strategy also provides a way to establish the detection modes for other biomolecules in plants.

Recent Advances in Electrochemical Enzyme-Based Biosensors for Food and Beverage Analysis

“…The biosensor prototype was reported to be practical by monitoring the glutamate level in situ by inserting the sensor directly into the tomato. The authors also claimed that the biosensor performed the widest detection range to date of 2 μM–16 mM [ 94 ]. This range is a suitable range for food application, for example, the glutamate content in watermelon is ~12 mM and around 10 mM in tomatoes.…”

“…Carboxylate groups were introduced to both GO and MWCNT, which was beneficial for fixing GlOx by EDC/NHS coupling. Both GO-COOH and MWCNT-COOH provided excellent catalytic properties and a large surface area for enzyme immobilisation [ 94 ].…”